1. Field of the Invention
The present invention relates, in general, to electric power supplies employing either or both DC—DC power converters and DC-AC power inverters.
2. Description of the Related Art
Often, the electrical requirements of a load are incompatible with the electrical characteristics of an available electrical power source. For example, the voltage of the load may be incompatible with the voltage of the power source (e.g., a 24 volt load and a 12 volt source), or the current type of the power source may be incompatible with the current type of the load (e.g., an AC load and a DC source or a DC load and an AC source). In such situations, an electric power supply may remedy the incompatibility.
An electric power supply is a “translation” circuit that typically provides power with the characteristics required by the load from an electric power source with characteristics which may be incompatible with the characteristics required by the load. To perform this function, a power supply typically uses one or more instances of two types of circuits in some combination. One type of circuit is a DC—DC converter, which converts between different DC voltage levels (i.e., conversion). The other type of circuit is an inverter, which changes DC power from a DC power source to AC power (i.e., inversion), or changes AC power from an AC power source to DC power (i.e., rectification). A combination of DC—DC converters and DC-AC inverters/rectifiers are frequently used to supply power to an AC load from a DC power source.
Those skilled in the art will appreciate that in certain applications, such as when the load is an electric motor of an electric drive automobile, the draw on the power supply can change relatively quickly in time (e.g., the amount of current drawn at the rated voltage may increase relatively quickly). For example, when the driver of the automobile needs maximum acceleration, such as to merge with traffic, the current drawn by the AC motor is likely to increase rapidly.
Those skilled in the art will appreciate that certain types of DC power sources, such as fuel cells, are relatively good at supplying steady output power, but may not have as suitable a short term response. Accordingly, a need exists in the art for a method and system to augment a DC power source when power drawn from that power source changes at a faster rate than that at which the power source can adequately respond.